Expression regulière php

Essaye qque chose du genre
? am?liorer :)
<?php
function test($teststring)
{
/*
array preg_split ( string pattern, string subject [, int limit [, int flags]])
*/
$results = preg_split("/\n/", $teststring);
if($results == null)
{
return "";
}
foreach($results as $line)
{
print("Ligne:" . $line. "\n");
}
}
<?php
$teststring= "Voici\ntrois\nlignes";
function test($teststring)
{
/*
array preg_split ( string pattern, string subject [, int limit [, int flags]])
*/
$results = preg_split("/\n/", $teststring);
if($results == null)
{
return "";
}
foreach($results as $line)
{
print("Ligne:" . $line. "\n");
}
}

test($teststring);
test("");

?>

test($teststring);
test("");
?>

The software said "Requires Windows98, Win2000, or better
So I installed Unix.